The hydrogen reduction behavior of the CuO-Co3O4 powder mixture for the synthesis of the homogeneous Cu-15at%Co composite powder has been investigated. The composite powder is prepared by ball milling the oxide powders, followed by a hydrogen reduction process. The reduction behavior of the ball-milled powder mixture is analyzed by X-ray diffraction (XRD) and temperature-programmed reduction at different heating rates in an Ar-10%H2 atmosphere. The scanning electron microscopy and XRD results reveal that the hydrogen-reduced powder mixture is composed of fine agglomerates of nanosized Cu and Co particles. The hydrogen reduction kinetics is studied by determining the degree of peak shift as a function of the heating rate. The activation energies for the reduction of the oxide powders estimated from the slopes of the Kissinger plots are 58.1 kJ/mol and 65.8 kJ/mol, depending on the reduction reaction: CuO to Cu and Co3O4 to Co, respectively. The measured temperature and activation energy for the reduction of Co3O4 are explained on the basis of the effect of pre-reduced Cu particles.

In this study, the temperature, the absolute humidity, and the turbulent flow characteristics of exhaust air and supply air in the mixer were studied while changing the shape of the mixer of the white smoke reducing heat exchange system. Using Solidworks, the mixer of the white smoke reduction heat exchange system was created by 3-D model. Also, the mixed flow of supply air and exhaust air inside the mixer under the uniform inlet conditions was computed, using the solidworks flow simulation. Two types of improvement models were selected by using a perforated plate and a guide vane as a turbulent mixing flow control method of the mixer. The mean temperature and mean absolute humidity of the mixture were greatly decreased according to the internal shapes of Case 1, 2, and 3. The temperature difference between the inlet and outlet of the mixer Case 3 was 26℃. The exit temperature and absolute humidity reduction rates of Case 3 were 26.2% and 48.1%, respectively, compared with Case 1.

ZnO thin-films are grown on a p-Si(111) substrate by RF sputtering. The effects of growth temperature and O2 mixture ratio on the ZnO films are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and roomtemperature photoluminescence (PL) measurements. All the grown ZnO thin films show a strong preferred orientation along the c-axis, with an intense ultraviolet emission centered at 377 nm. However, when O2 is mixed with the sputtering gas, the half width at half maximum (FWHM) of the XRD peak increases and the deep-level defect-related emission PL band becomes pronounced. In addition, an n-ZnO/p-Si heterojunction diode is fabricated by photolithographic processes and characterized using its current-voltage (I-V) characteristic curve and photoresponsivity. The fabricated n-ZnO/p-Si heterojunction diode exhibits typical rectifying I-V characteristics, with turn-on voltage of about 1.1 V and ideality factor of 1.7. The ratio of current density at ± 3 V of the reverse and forward bias voltage is about 5.8 × 103, which demonstrates the switching performance of the fabricated diode. The photoresponse of the diode under illumination of chopped with 40 Hz white light source shows fast response time and recovery time of 0.5 msec and 0.4 msec, respectively.

In this study, effects of gelatin extracted from chicken feet powder and wheat fiber on physicochemical properties of gel were determined. Gel samples were prepared with different concentrations of chicken feet gelatin powder (2, 3, and 4%) and wheat fiber (0, 1, and 2%). Gel strength increased (p<0.05) with increasing concentrations of both chicken feet gelatin powder and wheat fiber. In each gel sample, melting point and apparent viscosity of the gel was affected by different chicken feet gelatin powder concentrations irrespective of the wheat fiber concentrations (0, 1, or 2%). The 4% chicken feet gelatin powder induced the highest melting point among all gel samples regardless of the wheat fiber concentration. The gel sample with 4% chicken feet gelatin powder and 2% wheat fiber showed the highest values (p<0.05). With the increasing concentrations of wheat fiber, CIE L* increased in gel samples with chicken feet gelatin powder at 3 and 4% (p<0.05). Lower CIE a* was observed in gel samples with wheat fiber at 1 and 2% compared to gel samples without wheat fiber (p<0.05). CIE b* of gel samples with 2% chicken feet gelatin powder was decreased as increasing the addition level of wheat fiber (p<0.05). Consequently, our studies show that chicken feet gelatin powder and wheat fiber mixture could be used as a food ingredient since they have various effects on physicochemical properties of gel such as an effect on gel strength, melting point, viscosity, and color.

To understand the effect of high pressure on nitrogen oxides (NOx) formation in water added methane flames, opposed nonpremixed Water-methane/air (H2O-CH4/air) flames are numerically studied with high initial pressure. With GRI 3.0 detailed kinetic mechanism, NOx emissions are predicted for various strain rates. Due to high pressure, the chemical species are distributed in a narrow region, which means the thickness of the flame is thin. This can be clearly seen with high strain rate. Elevated pressure increases maximum temperature of flames which results in increased NOx emission. Even with elevated initial pressure, NOx emissions for H2O added methane flames are significantly decreased compare to pure methane flame. In addition, increased strain rate is also significant factor for decreasing NOx emission. With detailed rate of production analysis, in case of high pressure, it is confirmed that NO2 pathway is the most dominant reaction pathway than any other pathways.

In this study, velocity distribution characteristics by location and uniformity according to exit straight length in a 180° mixed pipes were numerically analyzed using RSM (Reynolds Stress Model) turbulent model by changing various flow parameters such as working fluids, inlet air velocity etc. As a result of it, the working fluids characteristics was highly indicated by the viscous force difference, the maximum velocity points according to main pipe’s inlet velocity were indicated when 90° sectional location was distributed at X/D=0.5~0.6 region and 180° sectional location was distributed at Y/D=0.5 region. And the flow characteristics according to branch pipe’s inlet velocity when 90° sectional location was distributed at X/D=0.4~0.6 region and 180° sectional location was distributed at Y/D=0.5 region. Based on the results that the most stable exit straight length in flow uniformity was indicated at L/D=25~30 region, 40D is suggested as the effective measurement distance in the straight pipe downstream curved pipe of mixed pipe.

This study examines paraelectric Bi1.5Zn1.0Nb1.5O7 (BZN), which has no hysteresis and high dielectric strength, for energy density capacitor applications. To increase the breakdown dielectric strength of the BZN film further, poly(vinylidene fluoride) BZN-PVDF composite film is fabricated by aerosol deposition. The volume ratio of each composition is calculated using dielectric constant of each composition, and we find that it was 12:88 vol% (BZN:PVDF). To modulate the structure and dielectric properties of the ferroelectric polymer PVDF, the composite film is heat-treated at 200 oC for 5 and 30 minutes following quenching. The amount of α-phase in the PVDF increases with an increasing annealing time, which in turn decreases the dielectric constant and dielectric loss. The breakdown dielectric strength of the BZN film increases by mixing PVDF. However, the breakdown field decreases with an increasing annealing time. The BZN-PVDF composite film has the energy density of 4.9 J/cm3, which is larger than that of the pure BZN film of 3.6 J/cm3.

화석연료로부터 기인한 환경오염에 대한 대응과 더불어 신재생에너지 공급의무화제도의 시행은 재생연료유 등 신재생에너지의 활용도를 증대시켰다. 부생연료유(2호)와 정제연료유(감압)는 국내 법령으로 엄격히 규제되고 있으며, 부생연료유(2호)를 혼합한 정제연료유(감압)의 물성변화를 시험하였다. 부생연료유(2호)를 1 : 1로 혼합한 정제연료유(감압)의 물성분석 결과, 국내 폐기물관리법에서 규정하고 있는 품질기준을 만족하였다. 다만, 연료와 관련한 추가항목 시험결과에서 높은 방향족 함량을 나타내었다. 연료내 높은 방향족 함량은 사용기기의 고무류 파손이나 연소 시 그을음, 매연 등이 발생할 가능성이 높을 것으로 보인다.

PURPOSES: The object of this study is to select appropriate inorganic materials, and find the best mixing formula to secure fast curing time and enough initial strength, and then to evaluate the durability of the asphalt mixtures according to the degree of addition of the compound manufactured by the determined blending ratio. METHODS : The breaking time and reactivity between seven kinds of inorganic minerals, and the selected recycled aggregate and emulsified asphalt were compared to determine the best initial curing strength for the mixtures. Then, three inorganic materials were chosen as the materials that provide good breaking time and reactivity, and the best mixing formula for the three materials was determined. The chemical composition of the compound manufactured using the mixing formula was analyzed by energy dispersive x-ray system method. Finally, indirect tensile strength (ITS) test was performed (for two days) at room temperature to determine the proper amount of additives that will provide the best initial strength. RESULTS: From the results of the reactivity test, the best mixing formula (A:C:G = 60:30:10) for the three selected inorganic materials with short braking time and high reactivity was determined. The four types of cold reclaimed asphalt mixtures for ITS testing were manufactured by adding the inorganic material compounds at 0%, 3%, 5%, and 7%, and the ITS values were measured after two curing days. The ITS values at 5% and 7% were 0.308 MPa and 0.415 MPa, respectively. The results of quality control tests (Marshall stability, porosity, flow value, etc.) at 5% and 7% satisfied the specification criterion for the cold recycled asphalt mixtures. CONCLUSIONS : The selected inorganic materials (A, C, and G) and the best mixing formula (A:C:G = 60:30:10) accelerated the reaction with emulsified asphalt and shortened the curing time. Depending on the inorganic material used, the breaking time and reactivity can be directly related or unrelated. This is because of the chemical compositions of recycled aggregates, infiltrated foreign matter, and chemical reactions between the inorganic materials and other materials. Therefore, it is important to select the proper materials and the best mixing formula when evaluating the characteristics of the practically used materials such as recycled aggregates, inorganic materials, and emulsified asphalt.

PURPOSES : The purpose of this study is to examine the manufacturing method for emulsified asphalt and its bond performance by analyzing the properties of the emulsifier used to produce cold recycled asphalt mixtures. METHODS: In this study, four types of slow-setting cationic emulsifiers, a microsurfacing emulsifier, and six types of nonionic emulsifiers were used to manufacture emulsified asphalt. Because each emulsifier requires its own unique effective dose to provide the best performance, the optimum asphalt content for each effective dose was determined. Then, the optimum asphalt content for the emulsified asphalt mixture was determined by the tests to check its basic physical properties. By using the determined optimum content, asphalt mixtures were manufactured and dynamic immersion and tensile strength tests were conducted on the mixtures to analyze the influence of the emulsifier on the physical properties of the mixtures. RESULTS : The dynamic immersion test results showed a coating ratio of 54-85%, which is considerably higher than that of using ordinary straight asphalt. The tensile strength test yielded noncompliant values less than 0.4 N/mm, which is the standard requirement for dry indirect tensile strength. The correlation analysis between the dynamic immersion and tensile strength ratio tests showed very high correlation of 0.78. The correlation between the emulsifier content and water resistance performance was low, between -0.55 and -0.24. CONCLUSIONS : While the storage stability improves with increasing emulsifier, the effectiveness proportional to the increase is weaker as the emulsifier increases. The performance testing of asphalt residues before and after manufacturing the emulsified asphalt showed no significant change. It is proved that the emulsified asphalt maintains high coating resistance according to the dynamic immersion test results. In addition, according to the results of tensile strength ratio, cold recycled asphalt mixtures manufactured by the materials normally and commercially used are not compliant with the national standard specification; thus, additional effective materials will be needed for quality compliance. In conclusion, it is evident that the dynamic immersion and tensile strength ratio tests have good correlation, but the quantity of emulsifiers used is not related to the level of moisture resistance.

식감과 기능성이 우수한 혼합잡곡의 혼합비율 설정을 위해 보리, 검정콩, 팥, 조, 기장, 수수, 찹쌀 등을 혼합하여 취반전후의 품질 및 이화학 특성을 조사하였다. 아밀로그램 특성은 혼합잡곡 처리구별로 유의적인 차이를 보였으며, 쌀에 혼합할 경우, 잡곡에 비해 최고점도, 최저점도, 강하점도 및 최종점도는 증가하는 경향을 보였다. 쌀을 혼합하지 않은 잡곡과 쌀을 70% 혼합한 잡곡의 수분결합력은 105.32~136.05 및 111.93~127.87%, 용해도는 각각 15.85~25.21 및 4.90~23.89%, 팽윤력은 각각 19.41~22.13 및 19.01~24.29%로 혼합잡곡 처리구별로 유의적인 차이를 보였다. 혼합잡곡을 일반밥솥으로 취반한 밥의 명도, 적색도 및 황색도는 각각 47.62~64.89, 0.83~3.54 및 3.33~8.11이었고, 압력밥솥으로 취반한 혼합잡곡밥은 각각 42.14~59.52, 1.40~4.22 및 3.93~7.32로 혼합잡곡 처리구별로 색도는 유의적인 차이를 보이는 것으로 나타났다. 일반밥솥으로 취반한 혼합잡곡밥의 경도, 탄력, 부착성 및 찰기는 각각 102.2~157.0, 55.1~83.3, 19.3~33.2 및 34.9~50.9, 압력밥솥으로 취반한 혼합잡곡밥은 각각 57.2~119.2, 37.9~ 63.9, 21.4~40.7 및 44.3~72.0으로 혼합잡곡 처리구별로 조직감은 유의적인 차이를 보였으며, 전체적으로 백미밥에 비해 경도와 탄력은 증가, 부착성과 찰기는 감소하는 경향을 보였다. 취반 전 혼합잡곡과 일반 및 압력밥솥으로 취반한 혼합잡곡밥의 총 폴리페놀 함량은 각각 4.46~5.16, 0.58~0.93 및 0.65~0.96 mg GAE/g, 총 플라보노이드 함량은 각각 250.74~ 548.89, 129.26~207.04 및 127.41~218.15 μg CE/g으로 나타났다. DPPH radical 소거활성은 각각 79.25~181.61, 22.07~53.64 및 7.51~39.97 mg TE/100 g, ABTS radical 소거활성은 각각 203.25~328.24, 47.28~84.94 및 58.27~99.51 mg TE/100 g으로 잡곡류의 혼합비율에 따라 유의적인 차이를 보였다. 이상의 결과, 취반방법에 따라 페놀 화합물 함량과 radical 소거활성을 차이를 보여 취반방법에 따라 잡곡의 종류를 달리할 필요가 있을 것으로 생각된다.

ZnO crystals with different morphologies are synthesized through thermal evaporation of the mixture of Zn and Cu powder in air at atmospheric pressure. ZnO crystals with wire shape are synthesized when the process is performed at 1,000 oC, while tetrapod-shaped ZnO crystals begin to form at 1,100 oC. The wire-shaped ZnO crystals form even at 1,000 oC, indicating that Cu acts as a reducing agent. As the temperature increases to 1,200 oC, a large quantity of tetrapod-shaped ZnO crystals form and their size also increases. In addition to the tetrapods, rod-shaped ZnO crystals are observed. The atomic ratio of Zn and O in the ZnO crystals is approximately 1:1 with an increasing process temperature from 1,000 oC to 1,200 oC. For the ZnO crystals synthesized at 1,000 oC, no luminescence spectrum is observed. A weak visible luminescence is detected for the ZnO crystals prepared at 1,100 oC. Ultraviolet and visible luminescence peaks with strong intensities are observed in the luminescence spectrum of the ZnO crystals formed at 1,200 oC.

본 연구에서는 항산화 활성이 높은 채소류를 혼합한 천연 발효식초의 제조 공정 확립을 연구목적으로 하여 채소류 6종의 생리학적 특성 조사 및 최적 배합 비율을 연구하였다. 이를 바탕으로 선정한 3종의 블랙베리, 케일, 당근을 적정 비율로 혼합하여 천연 발효식초 기술 개발과 함께 항산화 활성의 변화를 분석하였다. 따라서 블랙베리, 케일, 당근으로 배합비율과 공정 순서를 달리하여 AF-1부터 AF-6까지 시험구를 제조한 후 알코올발효 시켜 일반성분을 분석한 결과 케일과 당근 즉, 채소류를 10%(v/v) 첨가한 AF-1, AF-3, AF-5에서 pH 약 3.52와 산도 약 3.31%로 측정되었으며, 채소류를 20%(v/v) 첨가한 AF-2, AF-4, AF-6에서 pH 약 3.59와 산도 약 3.12%로 측정되었다. 알코올함량은 AF-1과 AF-2가 10.42%, 10.40% 순으로 높게 측정되어 비슷한 수준의 pH와 산도를 바탕으로 알코올 함량이 높게 측정된 AF-1과 AF-2를 최적 배합비율 및 발효공정으로 결정하였다. 이어 초산발효를 진행한 후 페놀성화합물을 측정한 결과 AAF-1이 14.95mg/100mL, AAF-2가 15.49mg/100mL로 측정되었으며, DPPH radical 소거능은 AAF-1이 40.48%, AAF-2가 53.97%로 측정되었다. ABTS′+ radical 소거능 또한 AAF-2가 65.02%로 측정되어 55.53%의 AAF-1보다 높게 나타나 유의적인 결과를 확인 할 수 있었다. 따라서 산도 7.00% 이상의 초산발효물 2종 중 명도(L)가 높고 총페놀성화합물 및 항산화 활성이 높은 AAF-2를 채소류 혼합 블랙베리 식초로 최종 선발하여 채소류 혼합 발효식초의 개발 가능성을 모색하였다.

PURPOSES: The objective of this study is to evaluate the physical properties of recycled asphalt mixtures reinforced with glass fiber. METHODS: Firstly, mixing design was conducted on recycled asphalt mixture for use of 50% recycled aggregate. Various laboratory tests were performed on four types of recycled asphalt mixtures with different glass fiber content to evaluate the physical properties. The laboratory tests include indirect tensile strength test, dynamic modulus test, Hamburg wheel tracking test and tensile-strength ratio to evaluate cracks, rutting and moisture resistance of mixtures. RESULTS: The indirect tensile strength of fiber reinforced glass increased about 139.4%. As a result of comparing the master curves obtained by the dynamic modulus test, the elasticity was low in the low temperature region and high in the high temperature region when the glass fiber was reinforced. The glass fiber contents of PEGS 0.3%, Micro PPGF 0.1% and Macro PPGF 0.3% showed the highest moisture resistance and rutting resistance. CONCLUSIONS : The test results show that use of glass fiber reinforcement can increase the resistance to cracking, rutting, and moisture damage of asphalt mixtures. It is also necessary to validate the long-term performance of recycled asphalt mixtures with glass fiber using full scale pavement testing and field trial construction.